Kaolinite

Last updated

Kaolinite
Kaolinite from Twiggs County in Georgia in USA.jpg
General
Category Phyllosilicates
Kaolinite-serpentine group
Formula
(repeating unit)
Al
2
(OH)
4
Si
2
O
5
Strunz classification 9.ED.05
Crystal system Triclinic
Crystal class Pedial (1)
(same H-M symbol)
Space group P1
Unit cell a = 5.13  Å, b = 8.89 Å
c = 7.25 Å; α = 90°
β = 104.5°, γ = 89.8°; Z = 2
Identification
ColorWhite to cream, sometimes red, blue or brown tints from impurities and pale-yellow; also often stained various hues, tans and browns being common.
Crystal habit Rarely as crystals, thin plates or stacked, More commonly as microscopic pseudohexagonal plates and clusters of plates, aggregated into compact, claylike masses
Cleavage Perfect on {001}
Tenacity Flexible but inelastic
Mohs scale hardness2–2.5
Luster Pearly to dull earthy
Streak White
Specific gravity 2.16–2.68
Optical propertiesBiaxial (–)
Refractive index nα = 1.553–1.565,
nβ = 1.559–1.569,
nγ = 1.569–1.570
2V angle Measured: 24° to 50°, Calculated: 44°
References [1] [2] [3]
Kaolinite
Traditional Chinese 高嶺石
Simplified Chinese 高岭石
Literal meaning"Gaoling stone"

Kaolinite ( /ˈkəlɪnt/ ) [4] [5] is a clay mineral, with the chemical composition Al 2 Si 2 O 5(OH)4. It is an important industrial mineral. It is a layered silicate mineral, with one tetrahedral sheet of silica (SiO
4
) linked through oxygen atoms to one octahedral sheet of alumina (AlO
6
) octahedra. [6] Rocks that are rich in kaolinite are known as kaolin /ˈkəlɪn/ or china clay. [7]

Contents

The name kaolin is derived from Gaoling (Chinese :高嶺; pinyin :Gāolǐng; lit. 'High Ridge'), a Chinese village near Jingdezhen in southeastern China's Jiangxi Province. [8] The name entered English in 1727 from the French version of the word: kaolin, following François Xavier d'Entrecolles's reports on the making of Jingdezhen porcelain. [9]

Kaolinite has a low shrink–swell capacity and a low cation-exchange capacity (1–15 meq/100 g). It is a soft, earthy, usually white, mineral (dioctahedral phyllosilicate clay), produced by the chemical weathering of aluminium silicate minerals like feldspar. In many parts of the world it is colored pink-orange-red by iron oxide, giving it a distinct rust hue. Lighter concentrations yield white, yellow, or light orange colors. Alternating layers are sometimes found, as at Providence Canyon State Park in Georgia, United States. Commercial grades of kaolin are supplied and transported as dry powder, semi-dry noodle, or liquid slurry.

Chemistry

Notation

The chemical formula for kaolinite as used in mineralogy is Al
2
Si
2
O
5
(OH)
4
, [3] however, in ceramics applications the formula is typically written in terms of oxides, thus the formula for kaolinite is Al
2
O
3
·2SiO
2
·2H2O
. [10]

Structure

Kaolinite structure, showing the interlayer hydrogen bonds Beevers crystal structure model of Kaolinite.jpg
Kaolinite structure, showing the interlayer hydrogen bonds

Compared with other clay minerals, kaolinite is chemically and structurally simple. It is described as a 1:1 or TO clay mineral because its crystals consist of stacked TO layers. Each TO layer consists of a tetrahedral (T) sheet composed of silicon and oxygen ions bonded to an octahedral (O) sheet composed of oxygen, aluminum, and hydroxyl ions. The T sheet is so called because each silicon ion is surrounded by four oxygen ions forming a tetrahedron. The O sheet is so called because each aluminum ion is surrounded by six oxygen or hydroxyl ions arranged at the corners of an octahedron. The two sheets in each layer are strongly bonded together via shared oxygen ions, while layers are bonded via hydrogen bonding between oxygen on the outer face of the T sheet of one layer and hydroxyl on the outer face of the O sheet of the next layer. [11]

A kaolinite layer has no net electrical charge and so there are no large cations (such as calcium, sodium, or potassium) between layers as with most other clay minerals. This accounts for kaolinite's relatively low ion exchange capacity. The close hydrogen bonding between layers also hinders water molecules from infiltrating between layers, accounting for kaolinite's nonswelling character. [11]

When moistened, the tiny platelike crystals of kaolinite acquire a layer of water molecules that cause crystals to adhere to each other and give kaolin clay its cohesiveness. The bonds are weak enough to allow the plates to slip past each other when the clay is being molded, but strong enough to hold the plates in place and allow the molded clay to retain its shape. When the clay is dried, most of the water molecules are removed, and the plates hydrogen bond directly to each other, so that the dried clay is rigid but still fragile. If the clay is moistened again, it will once more become plastic. [12]

Structural transformations

Kaolinite group clays undergo a series of phase transformations upon thermal treatment in air at atmospheric pressure.

Milling

Milling of the kaolinite results in the formation of a mechanochemically amorphized phase similar to metakaolin, although, the properties of this solid are quite different. [13] Huge energy is needed to transform the kaolinite into metakaolin.

Drying

Below 100 °C (212 °F), exposure to dry air will slowly remove liquid water from the kaolin. The end-state for this transformation is referred to as "leather dry". Between 100 °C and about 550 °C (1,022 °F), any remaining liquid water is expelled from kaolinite. The end state for this transformation is referred to as "bone dry". Throughout this temperature range, the expulsion of water is reversible: if the kaolin is exposed to liquid water, it will be reabsorbed and disintegrate into its fine particulate form. Subsequent transformations are not reversible, and represent permanent chemical changes.

Metakaolin

Endothermic dehydration of kaolinite begins at 550–600 °C producing disordered metakaolin, but continuous hydroxyl loss is observed up to 900 °C (1,650 °F). [14] Although historically there was much disagreement concerning the nature of the metakaolin phase, extensive research has led to a general consensus that metakaolin is not a simple mixture of amorphous silica (SiO
2
) and alumina (Al
2
O
3
), but rather a complex amorphous structure that retains some longer-range order (but not strictly crystalline) due to stacking of its hexagonal layers. [14]

Spinel

Further heating to 925–950 °C converts metakaolin to an aluminium-silicon spinel which is sometimes also referred to as a gamma-alumina type structure:

Platelet mullite

Upon calcination above 1050 °C, the spinel phase nucleates and transforms to platelet mullite and highly crystalline cristobalite:

Needle mullite

Finally, at 1400 °C the "needle" form of mullite appears, offering substantial increases in structural strength and heat resistance. This is a structural but not chemical transformation. See stoneware for more information on this form.

Occurrence

Kaolinite is one of the most common minerals; it is mined, as kaolin, in Malaysia, Pakistan, Vietnam, Brazil, Bulgaria, Bangladesh, France, the United Kingdom, Iran, Germany, India, Australia, South Korea, the People's Republic of China, the Czech Republic, Spain, South Africa, Tanzania and the United States. [1]

Mantles of kaolinitic saprolite are common in Western and Northern Europe. The ages of these mantles are Mesozoic to Early Cenozoic. [15]

Kaolinite clay occurs in abundance in soils that have formed from the chemical weathering of rocks in hot, moist climates—for example in tropical rainforest areas. Comparing soils along a gradient towards progressively cooler or drier climates, the proportion of kaolinite decreases, while the proportion of other clay minerals such as illite (in cooler climates) or smectite (in drier climates) increases. Such climatically-related differences in clay mineral content are often used to infer changes in climates in the geological past, where ancient soils have been buried and preserved. [16]

In the Institut National pour l'Etude Agronomique au Congo Belge (INEAC) classification system, soils in which the clay fraction is predominantly kaolinite are called kaolisol (from kaolin and soil). [17]

In the US, the main kaolin deposits are found in central Georgia, on a stretch of the Atlantic Seaboard fall line between Augusta and Macon. This area of thirteen counties is called the "white gold" belt; Sandersville is known as the "Kaolin Capital of the World" due to its abundance of kaolin. [18] [19] [20] In the late 1800s, an active kaolin surface-mining industry existed in the extreme southeast corner of Pennsylvania, near the towns of Landenberg and Kaolin, and in what is present-day White Clay Creek Preserve. The product was brought by train to Newark, Delaware, on the Newark-Pomeroy line, along which can still be seen many open-pit clay mines. The deposits were formed between the late Cretaceous and early Paleogene, about 100 to 45 million years ago, in sediments derived from weathered igneous and metakaolin rocks. [8] Kaolin production in the US during 2011 was 5.5 million tons. [21]

During the Paleocene–Eocene Thermal Maximum sediments deposited in the Esplugafreda area of Spain were enriched with kaolinite from a detrital source due to denudation. [22]

Synthesis and genesis

Difficulties are encountered when trying to explain kaolinite formation under atmospheric conditions by extrapolation of thermodynamic data from the more successful high-temperature syntheses (as for example Meijer and Van der Plas, 1980 [23] have pointed out). La Iglesia and Van Oosterwijk-Gastuche (1978) [24] thought that the conditions under which kaolinite will nucleate can be deduced from stability diagrams, based as they are on dissolution data. Because of a lack of convincing results in their own experiments, La Iglesia and Van Oosterwijk-Gastuche (1978) had to conclude, however, that there were other, still unknown, factors involved in the low-temperature nucleation of kaolinite. Because of the observed very slow crystallization rates of kaolinite from solution at room temperature Fripiat and Herbillon (1971) postulated the existence of high activation energies in the low-temperature nucleation of kaolinite.

At high temperatures, equilibrium thermodynamic models appear to be satisfactory for the description of kaolinite dissolution and nucleation, because the thermal energy suffices to overcome the energy barriers involved in the nucleation process. The importance of syntheses at ambient temperature and atmospheric pressure towards the understanding of the mechanism involved in the nucleation of clay minerals lies in overcoming these energy barriers. As indicated by Caillère and Hénin (1960) [25] the processes involved will have to be studied in well-defined experiments, because it is virtually impossible to isolate the factors involved by mere deduction from complex natural physico-chemical systems such as the soil environment. Fripiat and Herbillon (1971), [26] in a review on the formation of kaolinite, raised the fundamental question how a disordered material (i.e., the amorphous fraction of tropical soils) could ever be transformed into a corresponding ordered structure. This transformation seems to take place in soils without major changes in the environment, in a relatively short period of time, and at ambient temperature (and pressure).

Low-temperature synthesis of clay minerals (with kaolinite as an example) has several aspects. In the first place the silicic acid to be supplied to the growing crystal must be in a monomeric form, i.e., silica should be present in very dilute solution (Caillère et al., 1957; [27] Caillère and Hénin, 1960; [25] Wey and Siffert, 1962; [28] Millot, 1970 [29] ). In order to prevent the formation of amorphous silica gels precipitating from supersaturated solutions without reacting with the aluminium or magnesium cations to form crystalline silicates, the silicic acid must be present in concentrations below the maximum solubility of amorphous silica. The principle behind this prerequisite can be found in structural chemistry: "Since the polysilicate ions are not of uniform size, they cannot arrange themselves along with the metal ions into a regular crystal lattice." (Iler, 1955, p. 182 [30] )

The second aspect of the low-temperature synthesis of kaolinite is that the aluminium cations must be hexacoordinated with respect to oxygen (Caillère and Hénin, 1947; [31] Caillère et al., 1953; [32] Hénin and Robichet, 1955 [33] ). Gastuche et al. (1962), [34] as well as Caillère and Hénin (1962) have concluded, that only in those instances when the aluminium hydroxide is in the form of gibbsite, kaolinite can ever be formed. If not, the precipitate formed will be a "mixed alumino-silicic gel" (as Millot, 1970, p. 343 put it). If it were the only requirement, large amounts of kaolinite could be harvested simply by adding gibbsite powder to a silica solution. Undoubtedly a marked degree of adsorption of the silica in solution by the gibbsite surfaces will take place, but, as stated before, mere adsorption does not create the layer lattice typical of kaolinite crystals.

The third aspect is that these two initial components must be incorporated into one and the same mixed crystal with a layer structure. From the following equation (as given by Gastuche and DeKimpe, 1962) [35] for kaolinite formation

it can be seen, that five molecules of water must be removed from the reaction for every molecule of kaolinite formed. Field evidence illustrating the importance of the removal of water from the kaolinite reaction has been supplied by Gastuche and DeKimpe (1962). While studying soil formation on a basaltic rock in Kivu (Zaïre), they noted how the occurrence of kaolinite depended on the "degrée de drainage" of the area involved. A clear distinction was found between areas with good drainage (i.e., areas with a marked difference between wet and dry seasons) and those areas with poor drainage (i.e., perennially swampy areas). Only in the areas with distinct seasonal alternations between wet and dry was kaolinite found. The possible significance of alternating wet and dry conditions on the transition of allophane into kaolinite has been stressed by Tamura and Jackson (1953). [36] The role of alternations between wetting and drying on the formation of kaolinite has also been noted by Moore (1964). [37]

Laboratory syntheses

Syntheses of kaolinite at high temperatures (more than 100 °C [212 °F]) are relatively well known. There are for example the syntheses of Van Nieuwenberg and Pieters (1929); [38] Noll (1934); [39] Noll (1936); [40] Norton (1939); [41] Roy and Osborn (1954); [42] Roy (1961); [43] Hawkins and Roy (1962); [44] Tomura et al. (1985); [45] Satokawa et al. (1994) [46] and Huertas et al. (1999). [47] Relatively few low-temperature syntheses have become known (cf. Brindley and DeKimpe (1961); [48] DeKimpe (1969); [49] Bogatyrev et al. (1997) [50] ).

Laboratory syntheses of kaolinite at room temperature and atmospheric pressure have been described by DeKimpe et al. (1961). [51] From those tests the role of periodicity becomes convincingly clear. DeKimpe et al. (1961) had used daily additions of alumina (as AlCl
3
·6 H
2
O
) and silica (in the form of ethyl silicate) during at least two months. In addition, adjustments of the pH took place every day by way of adding either hydrochloric acid or sodium hydroxide. Such daily additions of Si and Al to the solution in combination with the daily titrations with hydrochloric acid or sodium hydroxide during at least 60 days will have introduced the necessary element of periodicity. Only now the actual role of what has been described as the "aging" (Alterung) of amorphous alumino-silicates (as for example Harder, 1978 [52] had noted) can be fully understood. Time as such is not bringing about any change in a closed system at equilibrium; but a series of alternations, of periodically changing conditions (by definition, taking place in an open system), will bring about the low-temperature formation of more and more of the stable phase kaolinite instead of (ill-defined) amorphous alumino-silicates.

Uses

The main use of the mineral kaolinite (about 50% of the time) is the production of paper; its use ensures the gloss on some grades of coated paper. [53]

Kaolin is also known for its capabilities to induce and accelerate blood clotting. In April 2008 the US Naval Medical Research Institute announced the successful use of a kaolinite-derived aluminosilicate infusion in traditional gauze, known commercially as QuikClot Combat Gauze, [54] which is still the hemostat of choice for all branches of the US military.

Kaolin is used (or was used in the past):

Geophagy

Humans sometimes eat kaolin for health or to suppress hunger, [60] a practice known as geophagy. Consumption is greater among women, especially during pregnancy. [61] This practice has also been observed within a small population of African-American women in the Southern United States, especially Georgia. [62] [63] There, the kaolin is called white dirt, chalk, or white clay. [62]

Safety

People can be exposed to kaolin in the workplace by breathing in the powder or from skin or eye contact.

United States

The Occupational Safety and Health Administration (OSHA) has set the legal limit (permissible exposure limit) for kaolin exposure in the workplace as 15 mg/m3 total exposure and 5 mg/m3 respiratory exposure over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 10 mg/m3 total exposure TWA 5 mg/m3 respiratory exposure over an 8-hour workday. [64]

Geotechnical engineering

Research results show that the utilization of kaolinite in geotechnical engineering can be alternatively replaced by safer illite, especially if its presence is less than 10.8% of the total rock mass. [65]

See also

Related Research Articles

Bauxite Sedimentary rock rich in aluminium

Bauxite is a sedimentary rock with a relatively high aluminium content. It is the world's main source of aluminium and gallium. Bauxite consists mostly of the aluminium minerals gibbsite (Al(OH)3), boehmite (γ-AlO(OH)) and diaspore (α-AlO(OH)), mixed with the two iron oxides goethite (FeO(OH)) and haematite (Fe2O3), the aluminium clay mineral kaolinite (Al2Si2O5(OH)4) and small amounts of anatase (TiO2) and ilmenite (FeTiO3 or FeO.TiO2). Bauxite appears dull in luster and is reddish-brown, white, or tan in color.

Clay Finely-grained natural rock or soil containing mainly clay minerals

Clay is a type of fine-grained natural soil material containing clay minerals. Clays develop plasticity when wet, due to a molecular film of water surrounding the clay particles, but become hard, brittle and non–plastic upon drying or firing. Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impurities, such as a reddish or brownish colour from small amounts of iron oxide.

Weathering Breaking down of rocks or other materials through exposure to the elements

Weathering is the breaking down of rocks, soils, and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs in situ, and should not be confused with erosion, which involves the transport of rocks and minerals by agents such as water, ice, snow, wind, waves and gravity.

Zeolites are microporous, aluminosilicate minerals commonly used as commercial adsorbents and catalysts. The term zeolite was originally coined in 1756 by Swedish mineralogist Axel Fredrik Cronstedt, who observed that rapidly heating a material, believed to have been stilbite, produced large amounts of steam from water that had been adsorbed by the material. Based on this, he called the material zeolite, from the Greek ζέω (zéō), meaning "to boil" and λίθος (líthos), meaning "stone". The classic reference for the field has been Breck's book Zeolite Molecular Sieves: Structure, Chemistry, And Use.

Sodium silicate Hygroscopic chemical compound of variable Na2O/SiO2 ratio precursor of waterglass

Sodium silicate is a generic name for chemical compounds with the formula Na
2x
Si
y
O
2y+x
or (Na
2
O)
x
·(SiO
2
)
y
, such as sodium metasilicate Na
2
SiO
3
, sodium orthosilicate Na
4
SiO
4
, and sodium pyrosilicate Na
6
Si
2
O
7
. The anions are often polymeric. These compounds are generally colorless transparent solids or white powders, and soluble in water in various amounts.

Clay mineral Hydrous aluminium phyllosilicates

Clay minerals are hydrous aluminium phyllosilicates, sometimes with variable amounts of iron, magnesium, alkali metals, alkaline earths, and other cations found on or near some planetary surfaces.

The pedosphere is the outermost layer of the Earth that is composed of soil and subject to soil formation processes. It exists at the interface of the lithosphere, atmosphere, hydrosphere and biosphere. The pedosphere is the skin of the Earth and only develops when there is a dynamic interaction between the atmosphere, biosphere, lithosphere and the hydrosphere. The pedosphere is the foundation of terrestrial life on Earth.

Dickite

Dickite is a phyllosilicate clay mineral named after the metallurgical chemist Allan Brugh Dick, who first described it. It is chemically composed of 20.90% aluminium, 21.76% silicon, 1.56% hydrogen and 55.78% oxygen. It has the same composition as kaolinite, nacrite, and halloysite, but with a different crystal structure (polymorph). Dickite sometimes contains impurities such as titanium, iron, magnesium, calcium, sodium and potassium.

Illite Group of related non-expanding clay minerals

Illite is a group of closely related non-expanding clay minerals. Illite is a secondary mineral precipitate, and an example of a phyllosilicate, or layered alumino-silicate. Its structure is a 2:1 sandwich of silica tetrahedron (T) – alumina octahedron (O) – silica tetrahedron (T) layers. The space between this T-O-T sequence of layers is occupied by poorly hydrated potassium cations which are responsible for the absence of swelling. Structurally, illite is quite similar to muscovite with slightly more silicon, magnesium, iron, and water and slightly less tetrahedral aluminium and interlayer potassium. The chemical formula is given as (K,H
3
O)(Al,Mg,Fe)
2
(Si,Al)
4
O
10
[(OH)
2
·(H
2
O)]
, but there is considerable ion (isomorphic) substitution. It occurs as aggregates of small monoclinic grey to white crystals. Due to the small size, positive identification usually requires x-ray diffraction or SEM-EDS analysis. Illite occurs as an altered product of muscovite and feldspar in weathering and hydrothermal environments; it may be a component of sericite. It is common in sediments, soils, and argillaceous sedimentary rocks as well as in some low grade metamorphic rocks. The iron-rich member of the illite group, glauconite, in sediments can be differentiated by x-ray analysis.

Orthosilicic acid chemical compound assumed present in dilute solutions of silicon dioxide in water

Orthosilicic acid is a chemical compound with formula Si(OH)
4
. It has been synthesized using non-aqueous solutions. It is assumed to be present when silicon dioxide (silica) SiO
2
dissolves in water at a millimolar concentration level.

Halloysite Aluminosilicate clay mineral

Halloysite is an aluminosilicate clay mineral with the empirical formula Al2Si2O5(OH)4. Its main constituents are oxygen (55.78%), silicon (21.76%), aluminium (20.90%), and hydrogen (1.56%). Halloysite typically forms by hydrothermal alteration of alumino-silicate minerals. It can occur intermixed with dickite, kaolinite, montmorillonite and other clay minerals. X-ray diffraction studies are required for positive identification. It was first described in 1826 and named after the Belgian geologist Omalius d'Halloy.

Aluminium silicate (or aluminum silicate) is a name commonly applied to chemical compounds which are derived from aluminium oxide, Al2O3 and silicon dioxide, SiO2 which may be anhydrous or hydrated, naturally occurring as minerals or synthetic. Their chemical formulae are often expressed as xAl2O3·ySiO2·zH2O. It is known as E number E559.

Aluminosilicate

Aluminosilicate minerals are minerals composed of aluminium, silicon, and oxygen, plus countercations. They are a major component of kaolin and other clay minerals.

Metakaolin is the anhydrous calcined form of the clay mineral kaolinite. Minerals that are rich in kaolinite are known as china clay or kaolin, traditionally used in the manufacture of porcelain. The particle size of metakaolin is smaller than cement particles, but not as fine as silica fume.

The Kaolin deposits of the Charentes Basin in France are clay deposits formed sedimentarily and then confined by other geological structures.

Geopolymers are inorganic, typically ceramic, alumino-silicate forming long-range, covalently bonded, non-crystalline (amorphous) networks. Obsidian fragments are a component of some geopolymer blends. Commercially produced geopolymers may be used for fire- and heat-resistant coatings and adhesives, medicinal applications, high-temperature ceramics, new binders for fire-resistant fiber composites, toxic and radioactive waste encapsulation and new cements for concrete. The properties and uses of geopolymers are being explored in many scientific and industrial disciplines: modern inorganic chemistry, physical chemistry, colloid chemistry, mineralogy, geology, and in other types of engineering process technologies. The field of geopolymers is a part of polymer science, chemistry and technology that forms one of the major areas of materials science.

Chamosite Phyllosilicate mineral member of the chlorite group

Chamosite is the Fe2+end member of the chlorite group. A hydrous aluminium silicate of iron, which is produced in an environment of low to moderate grade of metamorphosed iron deposits, as gray or black crystals in oolitic iron ore. Like other chlorites, it is a product of the hydrothermal alteration of pyroxenes, amphiboles and biotite in igneous rock. The composition of chlorite is often related to that of the original igneous mineral so that more Fe-rich chlorites are commonly found as replacements of the Fe-rich ferromagnesian minerals (Deer et al., 1992).

The pozzolanic activity is a measure for the degree of reaction over time or the reaction rate between a pozzolan and Ca2+ or calcium hydroxide (Ca(OH)2) in the presence of water. The rate of the pozzolanic reaction is dependent on the intrinsic characteristics of the pozzolan such as the specific surface area, the chemical composition and the active phase content.

Reverse weathering generally refers to the formation of a clay neoformation that utilizes cations and alkalinity in a process unrelated to the weathering of silicates. More specifically reverse weathering refers to the formation of authigenic clay minerals from the reaction of 1) biogenic silica with aqueous cations or cation bearing oxides or 2) cation poor precursor clays with dissolved cations or cation bearing oxides.

The soil matrix is the solid phase of soils, and comprise the solid particles that make up soils. Soil particles can be classified by their chemical composition (mineralogy) as well as their size. The particle size distribution of a soil, its texture, determines many of the properties of that soil, in particular hydraulic conductivity and water potential, but the mineralogy of those particles can strongly modify those properties. The mineralogy of the finest soil particles, clay, is especially important.

References

Citations

  1. 1 2 "Kaolinite mineral information and data". MinDat.org. Retrieved 5 August 2009.
  2. "Kaolinite Mineral Data". McDougall Minerals. Retrieved 5 August 2009.
  3. 1 2 Anthony JW, Bideaux RA, Bladh KW, et al., eds. (1995). "Kaolinite" (PDF). Handbook of Mineralogy: Silica, silicates. Tucson, Ariz.: Mineral Data Publishing. ISBN   9780962209734. OCLC   928816381.
  4. "kaolinite". Dictionary.com Unabridged. Random House.
  5. "Kaolinite". Oxford Dictionaries (online). 20 January 2016.
  6. Deer WA, Howie RA, Zussman J (1992). An Introduction to the Rock-forming Minerals (2nd ed.). Harlow: Longman. ISBN   9780470218099.
  7. Pohl WL (2011). Economic geology: principles and practice: metals, minerals, coal and hydrocarbons – introduction to formation and sustainable exploitation of mineral deposits. Chichester, West Sussex: Wiley-Blackwell. p. 331. ISBN   9781444336627.
  8. 1 2 Schroeder PA (31 July 2018). "Kaolin". New Georgia Encyclopedia (online). Retrieved 14 March 2019.
  9. Harper, Douglas. "kaolin". Online Etymology Dictionary .
  10. Perry DL (2011). Handbook of Inorganic Compounds (2nd ed.). Boca Raton: Taylor & Francis. ISBN   9781439814611. OCLC   587104373.
  11. 1 2 Nesse, William D. (2000). Introduction to mineralogy. New York: Oxford University Press. pp. 254–255. ISBN   9780195106916.
  12. Breuer, Stephen (July 2012). "The chemistry of pottery" (PDF). Education in Chemistry: 17–20. Retrieved 8 December 2020.
  13. Kasa E, Szabados M, Baan K, Konya Z, Kukovecz A, Kutus B, Palinko I, Sipos P (2021). "The dissolution kinetics of raw and mechanochemically treated kaolinites in industrial spent liquor – The effect of the physico-chemical properties of the solids". Appl. Clay Sci. 203: 105994. doi: 10.1016/j.clay.2021.105994 .
  14. 1 2 Bellotto M, Gualtieri A, Artioli G, et al. (1995). "Kinetic study of the kaolinite-mullite reaction sequence. Part I: kaolinite dehydroxylation". Phys. Chem. Miner. 22 (4): 207–214. Bibcode:1995PCM....22..207B. doi:10.1007/BF00202253. S2CID   95897543.
  15. Migoń P, Lidmar-Bergström K (2002). "Deep weathering through time in central and northwestern Europe: problems of dating and interpretation of geological record". Catena. 49 (1–2): 25–40. doi:10.1016/S0341-8162(02)00015-2.
  16. "Unraveling climatic changes from intraprofile variation in oxygen and hydrogen isotopic composition of goethite and kaolinite in laterites: an integrated study from Yaou, French Guiana". Geochimica et Cosmochimica Acta. 64 (3): 409–426. 1 February 2000. doi:10.1016/S0016-7037(99)00299-9. ISSN   0016-7037.
  17. Young A (1980). Tropical soils and soil survey. Cambridge Geographical Studies. 9. CUP Archive. p. 132. ISBN   9780521297684.
  18. "Kaolin Capital of the World". City of Sandersville, GA. Retrieved 27 August 2018.
  19. Reece C. "Making Peace With the Age-Old Practice of Eating White Dirt". The Bitter Southerner. Retrieved 27 August 2018.
  20. Smothers, Ronald (12 December 1987). "White George clay turns into cash". The New York Times. Retrieved 19 January 2021.
  21. Virta R (2012). Mineral Commodity Summaries (PDF) (Technical report). U.S. Geological Survey. pp. 44–45.
  22. Adatte T, Khozyem H, Spangenberg JE, et al. (2014). "Response of terrestrial environment to the Paleocene-Eocene Thermal Maximum (PETM), new insights from India and NE Spain". Rendiconti Online della Società Geologica Italiana. 31: 5–6. doi:10.3301/ROL.2014.17.
  23. Meijer EL, van der Plas L (1980). Relative stabilities of soil minerals. Mededelingen Landbouwhogeschool Wageningen. 80. Wageningen: Veenman. p. 18.
  24. La Iglesia A, Van Oosterwyck-Gastuche MC (1978). "Kaolinite Synthesis. I. Crystallization Conditions at Low Temperatures and Calculation of Thermodynamic Equilibria. Application to Laboratory and Field Observations". Clays and Clay Minerals. 26 (6): 397–408. Bibcode:1978CCM....26..397L. doi: 10.1346/CCMN.1978.0260603 .
  25. 1 2 Caillère S, Hénin S (1960). "Vues d'ensemble sur le problème de la synthèse des minéraux argileux à basse température". Bulletin du Groupe français des argiles (in French). 12 (7): 63. doi:10.3406/argil.1960.969.
  26. Fripiat JJ, Herbillon AJ (1971). "Formation and transformations of clay minerals in tropical soils". Soils and tropical weathering: proceedings of the Bandung Symposium 16 to 23 November 1969. Natural resources research. 11. Paris: Unesco. pp. 15–24. OCLC   421565.
  27. Caillère S, Hénin S, Esquevin J (1957). "Synthèse des minéraux argileux". Bulletin du Groupe français des argiles (in French). 9 (4): 67–76. doi:10.3406/argil.1957.940.
  28. Wey R, Siffert B (1961). "Réactions de la silice monomoléculaire en solutions avec les ions Al3+ et Mg2+". Colloques Internationaux (in French). Centre National des Recherches Scientifiques. 105: 11–23.
  29. Millot G (1970). Geology of Clays. Translated by Paquet H, Farrand WR. New York: Springer-Verlag. doi:10.1007/978-3-662-41609-9. ISBN   9783662416099.
  30. Iler RK (1955). The colloid chemistry of silica and silicates. Ithaca, N.Y.: Cornell University Press.
  31. Caillère S, Hénin S (1947). "Formation d'une phyllite du type kaolinique par traitement d'une montmorillonite". Comptes Rendus de l'Académie des Sciences de Paris. 224 (1): 53–55.
  32. Caillère S, Hénin S, Esquevin J (1953). "Recherches sur la synthèse des minéraux argileux". Bulletin de la Société française de Minéralogie et de Cristallographie (in French). 76 (7): 300–314. doi:10.3406/bulmi.1953.4841.
  33. Hénin S, Robichet O (1955). "Résultats obtenus au cours de nouveaux essais de synthèse de minéraux argileux". Bulletin du Groupe français des argiles (in French). 6 (1): 19–22. doi:10.3406/argil.1955.1257.
  34. Gastuche MC, Fripiat JJ, DeKimpe C (1962). "La genèse des minéraux argileux de la famille du kaolin. I. – Aspect colloidal". Colloque C.N.R.S. 105: 57–65.
  35. Gastuche MC, DeKimpe C (1962). "La genèse des minéraux argileux de la famille du kaolin. II. Aspect cristallin". Colloque C.N.R.S. 105: 75–88.
  36. Tamura T, Jackson ML (1953). "Structural and Energy Relationships in the Formation of Iron and Aluminum Oxides, Hydroxides, and Silicates". Science . 117 (3041): 381–383. Bibcode:1953Sci...117..381T. doi:10.1126/science.117.3041.381. PMID   17749950.
  37. Moore LR (1964). "The in Situ Formation and Development of Some Kaolinite Macrocrystals". Clay Minerals . 5 (31): 338–352. Bibcode:1964ClMin...5..338M. doi:10.1180/claymin.1964.005.31.02.
  38. van Nieuwenburg CJ, Pieters HA (1929). "Studies on hydrated aluminium silicates: I. The rehydration of metakaolin and the synthesis of kaolin". Recl. Trav. Chim. Pays-Bas . 48 (1): 27–36. doi:10.1002/recl.19290480106.
  39. Noll W (1934). "Hydrothermale Synthese des Kaolins". Zeitschrift für Kristallographie, Mineralogie und Petrographie (in German). 45 (2–3): 175–190. Bibcode:1934ZKMP...45..175N. doi:10.1007/BF02943371. S2CID   96869398.
  40. Noll W (1936). "Über die Bildungsbedingungen von Kaolin, Montmorillonit, Sericit, Pyrophyllit und Analcim". Zeitschrift für Kristallographie, Mineralogie und Petrographie (in German). 48 (3–4): 210–247. Bibcode:1936ZKMP...48..210N. doi:10.1007/BF02939458. S2CID   128744123.
  41. Norton FH (1939). "Hydrothermal formation of clay minerals in the laboratory". Am. Mineral. 24 (1): 1–17.
  42. Roy R, Osborn EF (1954). "The system Al
    2
    O
    3
    -SiO
    2
    -H
    2
    O
    "
    . Am. Mineral. 39 (11–12): 853–885.
  43. Roy R (1962). "The preparation and properties of synthetic clay minerals". Colloque C.N.R.S. 105: 83–98.
  44. Hawkins DB, Roy R (1962). "Electrolytic Synthesis of Kaolinite Under Hydrothermal Conditions". J. Am. Ceram. Soc. 45 (10): 507–508. doi:10.1111/j.1151-2916.1962.tb11044.x.
  45. Tomura S, Shibasaki Y, Mizuta H, et al. (1985). "Growth Conditions and Genesis of Spherical and Platy Kaolinite". Clays and Clay Minerals. 33 (3): 200–206. Bibcode:1985CCM....33..200T. doi: 10.1346/CCMN.1985.0330305 .
  46. Satokawa S, Osaki Y, Samejima S, et al. (1994). "Effects of the Structure of Silica-Alumina Gel on the Hydrothermal Synthesis of Kaolinite". Clays and Clay Minerals. 42 (3): 288–297. Bibcode:1994CCM....42..288S. doi: 10.1346/CCMN.1994.0420307 .
  47. Huertas FJ, Fiore S, Huertas F, et al. (1999). "Experimental study of the hydrothermal formation of kaolinite". Chemical Geology. 156 (1–4): 171–190. Bibcode:1999ChGeo.156..171H. doi:10.1016/S0009-2541(98)00180-6.
  48. Brindley GW, De Kimpe C (1961). "Attempted Low-Temperature Syntheses of Kaolin Minerals". Nature . 190 (4772): 254. Bibcode:1961Natur.190..254B. doi: 10.1038/190254a0 . S2CID   4149442.
  49. De Kimpe CR (1969). "Crystallization of kaolinite at low temperature from an alumino-silicic gel". Clays and Clay Minerals. 17 (1): 37–38. Bibcode:1969CCM....17...37D. doi: 10.1346/CCMN.1969.0170107 .
  50. Bogatyrev BA, Mateeva LA, Zhukov VV, et al. (1997). "Low-temperature synthesis of kaolinite and halloysite on the gibbsite – silicic acid solution system". Transactions (Doklady) of the Russian Academy of Sciences. Earth science sections. 353 A: 403–405.
  51. DeKimpe CR, Gastuche MC, Brindley GW (1961). "Ionic coordination in alumino-silicic acids in relation to clay mineral formation" (PDF). Am. Mineral. 46 (11–12): 1370–1381.
  52. Harder H (1978). "Synthesen von Tonmineralen unter spezieller Berücksichtigung festländischer Bedingungen". Schriftenreihe für geologische Wissenschaften (Berlin) (in German). 11: 51–78.
  53. Murray HH, Lyons SC (1955). "Correlation of Paper-Coating Quality with Degree of Crystal Perfection of Kaolinite". Clays and Clay Minerals. 4 (1): 31–40. Bibcode:1955CCM.....4...31M. doi: 10.1346/CCMN.1955.0040105 .
  54. Rowe A (24 April 2008). "Nanoparticles Help Gauze Stop Gushing Wounds". Wired. Condé Nast. Archived from the original on 6 July 2009. Retrieved 5 August 2009.
  55. "Stokoderm Protect PURE" (PDF). debgroup.com (product leaflet). Deb USA, Inc. 2017. Retrieved 12 April 2018.
  56. Ciullo PA (1996). Industrial Minerals and Their Uses: A Handbook and Formulary. Westwood, NJ: Noyes Publications. pp. 41–43. ISBN   9780815518082.
  57. Gracyk T (2006). "Edison Diamond Discs: 1912 - 1929". Tim Gracyk's Phonographs, Singers, & Old Records. Retrieved 22 March 2019.
  58. Diamond JM (1999). "Dirty eating for healthy living". Nature . Evolutionary biology. 400 (6740): 120–121. Bibcode:1999Natur.400..120D. doi: 10.1038/22014 . PMID   10408435.
  59. Leiviskä T, Gehör S, Eijärvi E, et al. (2012). "Characteristics and potential applications of coarse clay fractions from Puolanka, Finland". Open Eng. 2 (2): 239–247. Bibcode:2012CEJE....2..239L. doi: 10.2478/s13531-011-0067-9 .
  60. Kamtche F (2012). "Balengou: autour des mines" [Balengou: around the mines]. Le Jour (in French). Archived from the original on 4 March 2012. Retrieved 22 March 2019.
  61. Callahan GN (2003). "Eating Dirt". Emerg. Infect. Dis. CDC. 9 (8): 1016–1021. doi:10.3201/eid0908.ad0908. PMC   3020602 . PMID   12971372.
  62. 1 2 Grigsby RK (3 February 2004). "Clay Eating". New Georgia Encyclopedia (online). Science & Medicine. Retrieved 20 October 2019.
  63. Chen L (2 April 2014). "The Old And Mysterious Practice of Eating Dirt, Revealed". The Salt. NPR.
  64. "Kaolin". NIOSH Pocket Guide to Chemical Hazards. CDC . Retrieved 6 November 2015.
  65. Supandi, Supandi; Zakaria, Zufialdi; Sukiyah, Emi; Sudradjat, Adjat (29 August 2019). "The Influence of Kaolinite - Illite toward mechanical properties of Claystone". Open Geosciences. 11 (1): 440–446. doi: 10.1515/geo-2019-0035 .

General references